A pneumatic tire has conventionally been known of which a rolling resistance is reduced by reducing a ratio between a tread contact width and a tire section width (tread contact width/tire section width) (Patent Document 1, for example).
Such a pneumatic tire has a small tread contact width relative to the tire section width, and thus has a shape in which a gentle curve is drawn from a tread portion to a sidewall portion. Thus, an angle formed by a sidewall portion near a tread portion and a road surface is small and accordingly, the distance between the sidewall portion and the road surface is short. Thus, the sidewall portion is likely to come in contact with the road surface when the tire contact width increases outwardly in the tread width direction during cornering, when the pneumatic tire steps on a curbstone, or when an internal pressure of the pneumatic tire is low, for example.
Thus, in the pneumatic tire of Patent Document 1 described above, the sidewall portion is formed of a rubber material having excellent durability to prevent the sidewall portion from being damaged.
However, forming the sidewall portion of the rubber material having the excellent durability leads to an increase in amount of heat in the sidewall portion. This causes an energy loss which in turn increases the rolling resistance.